1. Field of the Invention
The subject invention generally relates to a polyurethane foam article and a method of forming the polyurethane foam article. More specifically, the subject invention relates to a method of forming a polyurethane foam article comprising the reaction product of an isocyanate-reactive resin composition, an isocyanate, and an indicator dye, in the presence of a blowing agent.
2. Description of the Related Art
Use of polyurethane foam articles throughout transportation, building, and other industries is known in the art. In the building industry, polyurethane foam articles are used to insulate structures. As insulation, a polyurethane foam article functions as a seamless and maintenance-free air barrier, which provides many benefits, such as prevention of moisture infiltration and mold growth and reduction of heating and air conditioning costs.
As is also known in the art, the polyurethane foam article is formed from an exothermic reaction of an isocyanate-reactive resin composition and an isocyanate in the presence of a blowing agent. The isocyanate-reactive resin composition, the isocyanate, and the blowing agent, collectively known as a polyurethane system, are selected to optimize application efficiency and performance properties of the polyurethane foam article for a particular use. For example, when using the polyurethane foam article to insulate structures, the components of the polyurethane system are selected such that the performance properties, e.g., insulative, adhesive, and other properties, of the polyurethane foam article formed therefrom are optimized.
To form the polyurethane foam article, the isocyanate-reactive resin composition and the isocyanate are typically mixed in the presence of the blowing agent to form a reaction mixture and the reaction mixture is applied as required for a particular use. The reaction mixture can be applied with an application technique, such as spraying, pouring, or injection molding. Like the components of the polyurethane system, the particular application technique is selected to optimize application efficiency and the performance properties of the polyurethane foam article for a particular use. Slight variations in the application technique affect the performance properties of the polyurethane foam article. Consequently, certain guidelines are often set forth for the application technique. For instance, when forming the polyurethane foam article to insulate structures, the reaction mixture is typically spray applied at a spray angle of 90° relative to a substrate, in well-defined and properly directed passes to form layers, or lifts. The lifts are typically between 12 and 50 mm thick. The lifts are spray applied for efficiency and to control an exotherm, which results from the exothermic reaction. Should the thickness of a lift exceed 50 mm, the exotherm generated could cause the lift to discolor, split, scorch, burn, inadequately adhere to the substrate, and other problems. If the polyurethane foam article having a desired thickness of greater than 50 mm is required, multiple lifts are formed to achieve the desired thickness. To form the polyurethane foam article having the desired thickness of greater than 50 mm, the reaction mixture is spray applied to form a first lift, the first lift is allowed to cool, and the reaction mixture is sprayed thereon to form a second lift. The first lift must cool prior to formation of the second lift so that the exotherm generated during the formation of the second lift is controlled such that the second lift does not discolor, split, scorch, burn, and/or inadequately adhere to the first lift at a pass-line, or interface, between the first and the second lift. Furthermore, the guidelines set for the application technique, as set forth above, are followed for the formation of additional lifts if required to achieve the desired thickness.
In the field, a contractor typically purchases the polyurethane foam system from a supplier. In turn, the contractor, who has contracted with a third party, applies the polyurethane system at a jobsite to form the polyurethane foam article. If the polyurethane foam article does not perform as expected, a field failure occurs, such as cracking, discoloration, blistering, adhesive failure, lift delamination, and/or poor insulation properties. When field failure occurs, warranty issues arise. When warranty issues arise, it is necessary to determine a root cause of the field failure so that a responsible party, typically either the supplier or the contractor, can be held accountable. Determining a root cause of the field failure can be difficult. This leaves the polyurethane foam system supplier and the contractor at odds.
The field failure can occur due to various reasons, such as quality problems with the polyurethane system, improper mixing of the polyurethane system, and improper application technique. For example, the field failure can occur when guidelines set forth for the spray application technique, as described above, are not followed. In some cases, lifts of improper thickness, i.e., lifts of greater than 50 mm, are formed to save time thereby resulting in field failure. In such cases, a cross-section of the polyurethane foam article can be visually examined, thickness of the lifts can be measured, the root cause of the failure can be determined, and responsibility for warranty issues can be placed on the contractor. In other cases, even though lifts of proper thickness are formed, the lifts are formed in quick succession with inadequate cooling. In such cases it is difficult to determine the root cause of the field failure that results.
In response to the needs outlined above, the polyurethane system has been developed to optimize the performance properties of the polyurethane foam article. In addition, the application technique has been selected and developed to ensure optimum performance of the polyurethane foam article as insulation. Despite such development, field failure still occurs and the need to determine the root cause for the field failure remains. As such, there remains a need to further improve the polyurethane foam article.